The present invention relates generally to semiconductor integrated circuit devices. More particularly, the present invention relates to a contactless local interconnect structure and the process for forming the same.
Local interconnect structures provide electrical and physical connection between semiconductor device features formed in close proximity to one another. The ever-increasing integration levels of semiconductor integrated circuit devices and the associated drive to reduce the sizes of individual components and cells renders local interconnect structures particularly useful in today""s advancing semiconductor manufacturing industry.
Conventional local interconnects are formed by forming contact windows in insulating materials formed over the features desired to be electrically connected. After the insulating material is formed over the structures, a contact window or windows are formed exposing portions of each of the features to be electrically connected to one another. One contact window may be formed exposing portions of each of the features to be electrically connected or dedicated contact windows may be separately formed to expose each feature. In some cases, stacked contact windows may be required to be formed in each of successively deposited insulating materials. In either case, a very precise alignment process must be carried out to insure that the contact windows are properly positioned. This is especially critical when feature sizes are reduced requiring a corresponding reduction in local interconnect feature sizes. In either case, after the contact window or windows are formed, a conductive material is formed within the contact window or windows in order to provide connection. Typically, after the conductive material is formed within the opening or openings, a planarization process such as chemical mechanical polishing (CMP) must be carried out to remove superfluous portions of the conductive material formed.
The process for forming and especially aligning the contact structure or structures is a time-consuming and costly process and is inherently risky because a tight alignment tolerance is required. Marginally aligned or misaligned contact windows commonly occur and can result in device failure. To address the limitations of conventional processing techniques, what is needed is a local interconnect structure and a process for producing the structure that reliably interconnects device features without the risks and processing difficulties associated with forming precisely aligned contacts.
To meet these and other needs, and in view of its purposes, the present invention provides a contactless local interconnect and a process for forming the same. The process includes forming a first silicon structure and a second silicon structure insulated form the first silicon structure by an insulating material. The process includes forming a continuous metal layer over the structures then heating to cause the metal film to react with the silicon of each of the first and second silicon structures to form a silicide film which bridges the gap formed by the insulating material, is a substantially continuous silicide film, and electrically couples the first silicon structure to the second silicon structure. The continuous silicide film serves as a local interconnect. The structure so formed includes a contactless local interconnect formed of a continuous silicide film connecting the first silicon structure to the second silicon structure. The structure preferably includes the first silicon structure overlapping portion of the second silicon structure and having a lateral edge extending over the second silicon structure. The silicide film is a continuous film which preferably extends over the lateral edge to connect the first silicon structure to the second silicon structure. Contact openings are not required as the silicide film is a self-aligned local interconnect.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but not restrictive, of the invention.